KR20100119043A - Method of driving light-source, apparatus for performing the method and display apparatus having the apparatus - Google Patents

Abstract

PURPOSE: A method of driving light-source, an apparatus for performing the method and a display apparatus having the apparatus are provided to stably drive the light source regardless of level of light source input voltage by raising a second output voltage being close to the reference voltage. CONSTITUTION: A panel power supply unit(140) changes the panel input voltage into the first direct current voltage. The panel power supply unit offers the gate on voltage and off voltage to a gate driving unit(130). A voltage conversion portion(150) comprises a common voltage generator(152) and a gamma voltage generator(154).

Description

A light source driving method, a light source driving apparatus for performing the same, and a display device including the same, the present invention relates to a light source driving apparatus and a display device including the same.

The present invention relates to a light source driving method, a light source driving apparatus for performing the same, and a display device including the same. More particularly, a light source driving method for stably driving a light source, a light source driving apparatus for performing the same, and the same It is to provide a display device.

In general, the liquid crystal display includes a liquid crystal display panel displaying an image using a light transmittance of the liquid crystal, and a backlight assembly disposed under the liquid crystal display panel to provide light to the liquid crystal display panel.

The liquid crystal display panel includes an array substrate having pixel electrodes and thin film transistors electrically connected to the pixel electrodes, a color filter substrate having a common electrode and color filters, and a liquid crystal layer interposed between the array substrate and the color filter substrate. It includes. The arrangement of the liquid crystal layer is changed by an electric field formed between the pixel electrodes and the common electrode, thereby changing the transmittance of light passing through the liquid crystal layer. Herein, when the light transmittance is increased to the maximum, the liquid crystal display panel may implement a white image having high luminance, whereas when the light transmittance is reduced to the minimum, the liquid crystal display panel may implement a black image having low luminance. .

Recently, a dimming technique is applied to reduce the amount of light of the backlight module according to an image and to increase the amount of light transmitted through the pixels of the liquid crystal display panel. The dimming technology has been developed in a light emitting diode module having a light emitting diode and is gradually applied to a lamp module having a lamp. In the backlight module to which the dimming technique is applied, the light source module is divided into linear light source blocks, and image regions corresponding to the light source blocks one to one are analyzed. The liquid crystal display panel of the liquid crystal display device is driven according to the increased gray level of the analyzed image region, and the backlight assembly is driven according to the brightness of the light source block reduced by the increase of the gray level.

However, the input voltages applied from the battery or the adapter to the light emitting block are stepped up or down depending on the design of the light source driver. Here, the boosting and depressurizing cannot be performed at the same time. Accordingly, as the number of light emitting diodes included in each light source block decreases, one of the input voltages applied from the battery and the adapter may not turn on the light emitting diodes.

The technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a light source driving method for driving the light source stably regardless of the level of the light source input voltage.

Another object of the present invention is to provide a light source driving apparatus for performing the light source driving method.

Another object of the present invention is to provide a display device including the light source driving device.

In the light source driving method according to an embodiment for achieving the above object of the present invention, the reference voltage and the light source input voltage is compared so that the first output voltage close to the light source input voltage or the second output voltage close to the reference voltage Is generated. Subsequently, a light source is driven based on either one of the first output voltage and the second output voltage.

In example embodiments, the first output voltage may be generated when the light source input voltage is less than the reference voltage, and the second output voltage may be generated when the light source input voltage is greater than or equal to the reference voltage.

In an embodiment of the present disclosure, generating the second output voltage may further include compensating the first output voltage to be closer to the reference voltage.

In an embodiment of the present disclosure, the method may further include generating a third output voltage by boosting the first output voltage and generating a fourth output voltage by boosting the second output voltage. The driving of the light source may be driving the light source based on any one of the first to fourth output voltages.

According to another aspect of the present invention, a light source driving apparatus includes a light source power supply unit and a light source driver. The light source power supply unit compares a reference voltage with a light source input voltage to generate a first output voltage close to the light source input voltage or the second output voltage close to the reference voltage. The light source driver drives the light source based on one of the first output voltage and the second output voltage.

In example embodiments, the light source power supply may generate the first output voltage when the light source input voltage is less than the reference voltage, and generate the second output voltage when the light source input voltage is greater than or equal to the reference voltage. have.

In an exemplary embodiment of the present invention, the light source power supply unit may include a switching device including an input terminal to which the light source input voltage is applied, a control terminal, and an output terminal connected to the light source driving unit, an anode connected to a ground terminal, and the switching device. It may include a Zener diode having a cathode connected to the control terminal.

In an embodiment of the present invention, the reference voltage may be a breakdown voltage of the control diode. The switching device may further include a resistor connected between the input terminal and the control terminal. It may further include a capacitor connected between the output terminal and the ground terminal of the switching element.

In an embodiment of the present invention, the light source power supply unit includes a switching element including an input terminal to which the light source input voltage is applied, a control terminal, and an output terminal connected to the light source driving unit, and a first terminal connected to the control terminal of the switching element. It may include a control diode having a diode, an anode connected to the ground terminal and a cathode connected to the first diode.

In an embodiment of the present invention, the cathode of the zener diode may be connected to the cathode of the first diode. The reference voltage may be a sum of the breakdown voltage of the zener diode and the correction voltage defined by the first diode.

In an embodiment of the present disclosure, the light source power supply may further include a second diode connected between an input terminal and an output terminal of the switching element.

In an embodiment of the present invention, the switching device may further include a resistor connected between the input terminal and the control terminal. It may further include a capacitor connected between the output terminal and the ground terminal of the switching element.

In an embodiment of the present disclosure, the voltage generator may further include a booster configured to boost the first output voltage and the second output voltage to generate a third output voltage and a fourth output voltage, and the light source driver may be configured to output the first to fourth outputs. The light source may be driven based on any one of voltages.

In an embodiment of the present invention, the light source driver includes a switching mode power supply (SMPS), and the booster is connected to the inductor connected between the light source power supply and the switching mode power supply, and the switching mode. It may include a third diode having a power supply and an anode connected to the inductor and a cathode connected to the light source.

According to another aspect of the present invention, a display device includes a display module and a backlight assembly. The display module receives light to display an image. The backlight assembly includes a light source unit, a light source power supply unit, and a light source driver. The light source unit includes a plurality of light source blocks to provide light to the display module. The light source power supply unit compares a reference voltage with a light source input voltage to generate a first output voltage close to the light source input voltage or the second output voltage close to the reference voltage. The light source driver drives the light source unit based on one of the first output voltage and the second output voltage.

In an embodiment of the present invention, the light source blocks may be arranged in one direction. The light source may include a plurality of light-emitting diodes (LEDs).

According to the present invention, even if the level of the light source input voltage is large, regardless of the number of light emitting diodes, the small second output voltage close to the reference voltage is boosted, so that the light source can be stably driven regardless of the level of the light source input voltage. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific form disclosed, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals are used for like elements in describing each drawing. In the accompanying drawings, the dimensions of the structure is shown in an enlarged scale than actual for clarity of the present invention. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, or combinations thereof. In addition, when a part of a layer, a film, an area, a plate, etc. is said to be above another part, this includes not only the case where it is directly over another part but also another part in the middle. Conversely, if a part of a layer, film, region, plate, etc. is under another part, this includes not only the part directly under another part but also another part in the middle.

Example 1

1 is a block diagram illustrating a display device according to a first exemplary embodiment of the present invention.

Referring to FIG. 1, a display device according to Embodiment 1 of the present invention includes a panel module 100 and a backlight assembly 200.

The panel module 100 includes a display panel 110, a data driver 120, a gate driver 130, a panel power supply 140, and a voltage converter 150.

An external battery (not shown) or an adapter (not shown) directly provides the panel input voltage Vi1 to the panel power supply 140.

The panel power supply 140 converts the panel input voltage Vi1 into a first DC voltage and provides the gate driver 130 with a gate on voltage VON and an off voltage VOFF.

The voltage converter 150 includes a common voltage generator 152 and a gamma voltage generator 154.

The common voltage generator 152 receives the first DC voltage from the panel power supply 140, generates a common voltage VCOM, and provides the common voltage VCOM to the display panel 110.

The gamma voltage generator 154 receives the first DC voltage from the panel power supply 140, generates a gamma voltage VDD, and provides the gamma voltage VDD to the data driver 120.

The data driver 120 provides the gray scale display voltage corresponding to the data gray scale to the display panel 110 using the gamma voltage VDD. The level-converted first DC voltage provided to the gamma voltage generator 154 may be a gamma reference power source.

The display panel 110 generates the gray scale display voltage and the common voltage provided from the data driver 120 in response to the gate on / off voltage VON / VOFF provided from the gate driver 130. The common voltage VCOM provided from the unit 152 is applied to a liquid crystal layer (not shown) interposed between an upper substrate (not shown) and a lower substrate (not shown) of the display panel 110 to display data. do.

The backlight assembly 200 includes a light source unit 210 and a light source driving device 220.

The light source unit 210 includes a plurality of light source blocks.

The light source power supply 222 receives a light source input voltage Vi2 from an external battery (not shown) or an adapter (not shown). The battery outputs a voltage of about 8V to about 13.2V to the light source power supply 222, and the adapter outputs a voltage of about 19.5V to the light source power supply 222.

The light source power supply unit 222 converts the light source input voltage Vi2 into a second DC voltage Vo11 and provides the light source driver 224.

According to the level of the light source input voltage Vi2, the level of the second DC voltage Vo11 may vary. For example, when the light source input voltage Vi2 is less than a reference voltage, the second DC voltage Vo11 is generated as a first output voltage close to the light source input voltage Vi2. On the other hand, when the light source input voltage Vi2 is equal to or greater than the reference voltage, the second DC voltage Vo11 is generated as a second output voltage close to the reference voltage.

The second DC voltage Vo11 passing through the light source driver 224 is boosted to a third DC voltage Vo12 and provided to the light source unit 210. For example, the third DC voltage Vo12 includes a third output voltage boosted by the first output voltage and a fourth output voltage boosted by the second output voltage. As another example, the third DC voltage Vo12 may include the first output voltage and the second output voltage.

The light source driver 224 determines a luminance representative value according to an external image signal (not shown) corresponding to each light source block, and the third light source according to the dimming level in each light source block corresponding to the luminance representative value. A driving signal is generated based on the DC voltage Vo12 and provided to the light source unit 210.

For example, the light source driver 224 divides the image signal in units of frames into a plurality of image regions by using the image signal, and obtains maximum gray scale data and average gray scale data of each image region. Subsequently, the light source driver 224 determines the luminance representative value using the maximum gray scale data and the average gray scale data. Subsequently, the light source driver 224 determines the duty ratios corresponding to each light source block based on the luminance representative value. In this case, the light source driving unit 224 generates the driving signal based on the duty ratios, and provides the driving signal to the light source unit 210.

Each light source block of the light source unit 210 generates light based on the driving signal. The display panel 110 may receive the light to display the image signal.

FIG. 2 is a circuit diagram illustrating the backlight assembly of FIG. 1.

3A to 3C are voltage waveform diagrams applied to a control terminal, an input terminal, and an output terminal of the light source power supply of FIG. 2. Here, the X axis represents time (T) and the Y axis represents voltage (V).

1 to 3C, the light source power supply unit 222 includes a resistor R, a zener diode ZD, a switching element SW, and a capacitor C. Referring to FIGS.

The zener diode ZD has the reference voltage Vref1 as the breakdown voltage.

The switching element SW includes an input terminal to which the light source input voltage Vi2 is applied, a control terminal connected to one end of the cathode of the zener diode ZD, and an output terminal to which the second DC voltage Vo11 is output. do. The resistor R is connected between the input terminal and the control terminal. One end of the capacitor C is connected to the output terminal. An anode of the zener diode ZD and the other end of the capacitor C are connected to a ground terminal.

When the light source input voltage Vi2 is applied to the switching element SW, a value close to the light source input voltage Vi2 or a value close to the reference voltage Vref according to the magnitude of the light source input voltage Vi2. This is generated as the first DC voltage Vo11.

When the switching element SW is applied with the light source input voltage Vi2 having a value smaller than the reference voltage Vref1, the switching element SW outputs a value close to the light source input voltage Vi2 with the first output. Output as voltage.

 On the other hand, when the switching device SW receives the light source input voltage Vi2 having a value equal to or greater than the reference voltage Vref1, the switching device SW receives a value close to the reference voltage Vref1. It outputs as a 2nd output voltage.

The light source driver 224 includes a switching mode power supply (SMPS).

The light source driving device 220 further includes a boosting unit 226 connected to the switching mode power supply to boost the first output voltage or the second output voltage to the third output voltage or the fourth output voltage. can do.

The booster 226 includes an inductor L and a diode D.

One end of the inductor L is connected to the output terminal of the switching element SW. The cathode of the diode D is connected to the light source unit 210. The other end of the inductor L and the anode of the diode D are connected with the switching mode power supply.

Accordingly, the second DC voltage Vo11 output from the output terminal may be boosted to the third DC voltage Vo12 which is a voltage of a level that can be used by the light source unit 210. Here, the light source unit 210 may use the second DC voltage Vo11 as the third DC voltage Vo12 without boosting.

The light source unit 210 is divided into a plurality of light source blocks B1,..., Bn. Each of the light source blocks B1, ..., Bn includes a plurality of light sources L1, L2, ..., Li. Where i and n are natural numbers.

The light sources are light-emitting diodes (LEDs).

The light source blocks B1, ..., Bn are turned on or off for each block in response to the driving signal. The light source blocks B1, ..., Bn may be locally dimmed in one direction for each block.

In this embodiment, it has been described that the one-dimensional dimming method in which the light source blocks and the image regions are arranged in one direction is applied to a backlight assembly. Meanwhile, a two-dimensional dimming method in which the light source blocks are divided into a matrix and correspondingly divided the image regions into a matrix may be applied to a backlight assembly. Similarly, a 0-dimensional dimming method in which the light source unit 210 is formed of one light source block may be applied to the backlight assembly.

The light source unit 210 includes the light source blocks B1, ..., Bn, and each of the light source blocks B1, ..., Bn is the light sources L1, L2, ..., Li). Therefore, a voltage capable of driving the light sources L1, L2, ..., Li should be applied block by block to the light source blocks B1, ..., Bn. Here, the voltage capable of driving the light sources L1, L2, ..., Li is the third DC voltage Vo12 corresponding to 'i' light sources L1, L2, ..., Li. )to be.

For example, a voltage of about 3V to about 3.4V is required for each of the light sources L1, L2, ..., Li to turn on the light sources L1, L2, ..., Li. .

That is, when 'i' is 5, the third DC voltage Vo12 is about 15V to 17V, and when 'i' is 6, the third DC voltage Vo12 is about 18V to about 20.4V.

When 'i' is 7, the third DC voltage Vo12 is about 21V to 23.8V, and when 'i' is 8, the third DC voltage Vo12 is about 24V to about 27.2V.

When 'i' is 9, the third DC voltage Vo12 is about 27V to 30.6V, and when 'i' is 10, the third DC voltage Vo12 is about 30V to about 34V.

The light source driver 224 may turn on or turn off the light source blocks B1,..., And Bn on a block-by-block basis based on the third DC voltage Vo12.

Since the battery outputs a voltage of about 8V to about 13.2V and the adapter outputs a voltage of about 19.5V, when the i is 5, the third DC voltage Vo12 may be at least about 15V. Therefore, the reference voltage Vref1 may be implemented at about 10V to about 15V. In the present embodiment, the reference voltage Vref1 is implemented at 12V.

The second DC voltage Vo11 may have a value close to the reference voltage Vref1. Accordingly, the second DC voltage Vo11 passing through the light source driver 224 and the booster 226 may turn on at least five light sources L1, L2,..., Li. The third DC voltage Vo12 may be boosted or the second DC voltage Vo11 may be output as the third DC voltage Vo12. Here, when the five or more light sources L1, L2,..., Li are turned on, the third DC voltage Vo12 less than the reference voltage Vref1 is not necessary, and thus, the light source driver 224. The boosting unit 226 to which the switching mode power supply, which is included, has only a boosting function.

In the present embodiment, the case in which the five or more light sources L1, L2, ..., Li are turned on as an example, but the number of the light sources L1, L2, ..., Li is about 4 Dogs to about 12 dogs.

In the case of turning on less than five light sources, the reference voltage Vref1 may be reduced.

Referring again to FIGS. 3A to 3C, when the reference voltage Vref1 is 12V, a change in the second DC voltage Vo11 according to the level of the light source input voltage Vi2 may be known.

For example, when the light source input voltage Vi2 of 8V is applied to the input terminal, the zener diode ZD is smaller than the breakdown voltage which is the reference voltage Vref1. It is turned off. Accordingly, the first output voltage, which is the voltage Vc1 and the second DC voltage Vo11 applied to the zener diode ZD, increases for about 0.03 ms after the light source input voltage Vi2 is applied, It can be seen that the final values are 8V and about 7.4V.

When the light source input voltage Vi2 of 13.2V is applied to the input terminal, the zener diode ZD is turned on since the light source input voltage Vi2 is greater than the breakdown voltage which is the reference voltage Vref1. do. Accordingly, it can be seen that the voltage Vc1 of the zener diode ZD increases for about 0.03 ms after the light source input voltage Vi2 is applied, and reaches a final value of 12 V which is the breakdown voltage. The second output voltage of the second DC voltage Vo11 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and reaches a final value close to the breakdown voltage of 12V. Here, it can be seen that the second output voltage is a final value of about 12.5V, which is 0.5V greater than the breakdown voltage.

When the light source input voltage Vi2 of 19.5V is applied to the input terminal, the zener diode ZD is turned on since the light source input voltage Vi2 is greater than the breakdown voltage which is the reference voltage Vref1. do. Accordingly, it can be seen that the voltage Vc1 of the zener diode ZD increases for about 0.03 ms after the light source input voltage Vi2 is applied, and reaches a final value of 12 V which is the breakdown voltage. The second output voltage of the second DC voltage Vo11 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and reaches a final value close to the breakdown voltage of 12V. Here, it can be seen that the second output voltage is a final value of about 12.5V, which is 0.5V greater than the breakdown voltage.

4 is a flowchart illustrating a light source driving method of the light source driving apparatus of FIG. 1.

1 and 4, when the light source input voltage Vi2 is applied to the input terminal, the reference voltage Vref1 and the light source input voltage Vi2, which are the breakdown voltage of the zener diode ZD, The comparison is made (step S110).

Subsequently, when the light source input voltage Vi2 is checked to be less than the reference voltage Vref1, the first output voltage, which is the second DC voltage Vo11 that is close to the light source input voltage Vi2, is generated (step S120). . On the other hand, when the light source input voltage Vi2 is checked to be equal to or greater than the reference voltage Vref1, the second output voltage, which is the second DC voltage Vo11 close to the reference voltage Vref1, is generated (step S130).

The second DC voltage Vo11 includes the third and fourth output voltages by the switching mode power supply of the light source driver 224 connected between the inductor L and the diode D. The voltage is boosted as three DC voltages Vo12 (step S140). The third DC voltage Vo12 may also include the first and second output voltages. Accordingly, the light source driver 224 drives the light source unit 210 based on the third DC voltage Vo12 (step S150).

According to the present embodiment, the light source power supply unit 222 may approach the light source input voltage Vi2 or the second direct current close to the reference voltage Vref1 regardless of the level of the light source input voltage Vi2. By outputting the voltage Vo11, both the small number of the light emitting diodes and the large number of the light emitting diodes can be turned on using only the boosting circuit. Accordingly, the display device according to the present exemplary embodiment may use both a battery and an adapter for applying various levels of the light source input voltage Vi2.

Example 2

5 is a circuit diagram illustrating a backlight assembly according to a second embodiment of the present invention.

6A through 6C are voltage waveform diagrams applied to a control terminal, an input terminal, and an output terminal of the light source power supply of FIG. 5. Here, the X axis represents time (T) and the Y axis represents voltage (V).

In the display device according to the second exemplary embodiment, the light source power supply unit 322 further includes a first diode D1 and a second diode D2 such that the second DC voltage Vo21 and the third DC voltage Vo22 are applied. Except that different from the second DC voltage Vo11 and the third DC voltage Vo12 in FIG. 1, the display device is substantially the same as the display device according to the first exemplary embodiment shown in FIG. 1. Accordingly, corresponding elements are denoted by corresponding reference numerals, and redundant descriptions are omitted.

1, 5 and 6A to 6C, the first diode D1 is connected in series with the zener diode ZD such that the second DC voltage Vo21 is closer to the reference voltage Vref2. The reference voltage Vref2 is compensated for. The cathode of the first diode D1 is connected to the cathode of the zener diode ZD, and the anode of the first diode D1 is connected to the control terminal of the switching element SW.

The light source power supply 322 may further include a second diode D2 connected between the input terminal and the output terminal of the switching element SW. The cathode of the second diode D2 is connected to the input terminal of the switching element SW, and the anode of the second diode D2 is connected to the output terminal of the switching element SW. The second DC voltage Vo21 may be closer to the reference voltage Vref2 by the second diode D2.

In detail, the reference voltage Vref2 may be greater than the breakdown voltage of the zener diode ZD by a compensation voltage. That is, the second DC voltage Vo21 may be closer to the reference voltage Vref2 by the first and second diodes D1 and D2. Here, the reference voltage Vref2 is about 12.6V. Therefore, the heat generated by the voltage drop in the light source power supply 322 may be reduced.

For example, when the light source input voltage Vi2 of 8V is applied to the input terminal, the zener diode ZD is turned off because the light source input voltage Vi2 is smaller than the reference voltage Vref2. . Therefore, the sum Vc2 of the voltages applied to the zener diode ZD and the first diode D1 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and reaches a final value of about 8 V. Able to know. The first output voltage which is the second DC voltage Vo21 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and then reaches a final value of about 7.4V.

When the light source input voltage Vi2 of 13.2V is applied to the input terminal, the zener diode ZD is turned on because the light source input voltage Vi2 is greater than the reference voltage Vref2. Accordingly, the sum Vc2 of the voltages applied to the zener diode ZD and the first diode D1 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and then the breakdown voltage of 12.6 V is increased. It can be seen that the final value. The second output voltage of the second DC voltage Vo21 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and reaches a final value close to 12.6 V of the reference voltage Vref2. Here, it can be seen that the second output voltage becomes a final value of about 12.7V, which is 0.1V greater than the reference voltage Vref2.

When the light source input voltage Vi2 of 19.5V is applied to the input terminal, the zener diode ZD is turned on because the light source input voltage Vi2 is greater than the reference voltage Vref2. Therefore, the sum Vc2 of the voltages applied to the zener diode ZD and the first diode D1 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and then becomes the reference voltage Vref2. It can be seen that the final value of 12.6V. The second output voltage of the second DC voltage Vo21 increases for about 0.03 ms after the light source input voltage Vi2 is applied, and reaches a final value close to 12.6 V of the reference voltage Vref2. Here, it can be seen that the second output voltage is a final value of about 12.7V, which is 0.1V greater than the breakdown voltage.

Therefore, the difference between the reference voltage Vref2 and the second DC voltage Vo21 is 0.1V, which is smaller than 0.5V, which is the difference between the reference voltage Vref1 and the second DC voltage Vo11 of Example 1. Able to know. Specifically, the reference voltage Vref2 may be compensated by the compensation voltage of 0.4V.

7 is a flowchart illustrating a light source driving method of the light source driving apparatus of FIG. 5.

5 and 7, when the light source input voltage Vi2 is applied to the input terminal, the reference voltage Vref2 and the light source input voltage Vi2 are compared (step S210).

Subsequently, when the light source input voltage Vi2 is checked to be less than the reference voltage Vref2, the first output voltage that is the second DC voltage Vo21 that is close to the light source input voltage Vi2 is generated (step S220). . On the other hand, when the light source input voltage Vi2 is checked to be equal to or greater than the reference voltage Vref2, the second output voltage, which is the second DC voltage Vo21 that is close to the reference voltage Vref2, is generated (step S230). Here, the reference voltage Vref2 is compensated to be closer to the second output voltage (step S235).

The second DC voltage Vo21 includes the third and fourth output voltages by the switching mode power supply of the light source driver 224 connected between the inductor L and the diode D. The voltage is boosted as three DC voltages Vo22 (step S240). The third DC voltage Vo12 may also include the first and second output voltages. Accordingly, the light source driver 224 drives the light source unit 210 based on the third DC voltage Vo22 (step S250).

According to the present exemplary embodiment, the reference voltage Vref2 close to the second output voltage may be reduced so that the difference between the reference voltage Vref2 and the second output voltage may be easily output. It is possible to design the light source power supply unit 322 having a).

According to embodiments of the present invention, regardless of the number of light emitting diodes, even if the level of the light source input voltage is large, the second output voltage close to the reference voltage may be boosted or output as it is and used to drive the light source. Accordingly, it is possible to prevent the driving failure of the light emitting diodes, which may occur due to neither the boosting nor the depressurization of various levels of the light source input voltages applied from the battery or the adapter.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

1 is a block diagram illustrating a display device according to a first exemplary embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating the backlight assembly of FIG. 1.

3A to 3C are voltage waveform diagrams applied to a control terminal, an input terminal, and an output terminal of the light source power supply of FIG. 2.

4 is a flowchart illustrating a light source driving method of the light source driving apparatus of FIG. 1.

5 is a circuit diagram illustrating a backlight assembly according to a second embodiment of the present invention.

6A through 6C are voltage waveform diagrams applied to a control terminal, an input terminal, and an output terminal of the light source power supply of FIG. 5.

7 is a flowchart illustrating a light source driving method of the light source driving apparatus of FIG. 5.

<Description of the symbols for the main parts of the drawings>

100: display module 110: display panel

120: data driver 130: gate driver

140: panel power supply unit 150: voltage conversion unit

152: common voltage generator 154: gamma voltage generator

200: backlight assembly 210: light source

220: light source driving device 222: light source power supply

224: light source driving unit

Claims (20)

Comparing a reference voltage with a light source input voltage to generate a first output voltage close to the light source input voltage or a second output voltage close to the reference voltage; And And driving a light source based on one of the first output voltage and the second output voltage. The method of claim 1, wherein the first output voltage is generated when the light source input voltage is less than the reference voltage, and the second output voltage is generated when the light source input voltage is greater than or equal to the reference voltage. . The method of claim 1, wherein generating the second output voltage further comprises compensating the first output voltage to be closer to the reference voltage. The method of claim 1, further comprising: boosting the first output voltage to generate a third output voltage; And Boosting the second output voltage to generate a fourth output voltage; The driving of the light source may include driving the light source based on any one of the first to fourth output voltages. A light source power supply unit configured to compare a reference voltage and a light source input voltage to generate a first output voltage close to the light source input voltage or the second output voltage close to the reference voltage; And And a light source driver configured to drive a light source based on any one of the first output voltage and the second output voltage. The method of claim 5, wherein the light source power supply unit generates the first output voltage when the light source input voltage is less than the reference voltage, and generates the second output voltage when the light source input voltage is greater than or equal to the reference voltage. A light source drive device. The method of claim 5, wherein the light source power supply unit, A switching element including an input terminal to which the light source input voltage is applied, a control terminal, and an output terminal connected to the light source driver; And And a Zener diode having an anode connected to a ground terminal and a cathode connected to a control terminal of the switching element. The light source driving apparatus of claim 7, wherein the reference voltage is a breakdown voltage of the control diode. The light source driving apparatus of claim 7, further comprising a resistor connected between the input terminal and the control terminal of the switching element. 8. The light source driving apparatus of claim 7, further comprising a capacitor connected between the output terminal of the switching element and the ground terminal. The method of claim 5, wherein the light source power supply unit, A switching element including an input terminal to which the light source input voltage is applied, a control terminal, and an output terminal connected to the light source driver; A first diode connected to a control terminal of the switching element; And And a control diode having an anode connected to the ground terminal and a cathode connected to the first diode. 12. The light source driving apparatus of claim 11, wherein the cathode of the zener diode is connected to the cathode of the first diode. The light source driving device of claim 11, wherein the reference voltage is a sum of a breakdown voltage of the zener diode and a correction voltage defined by the first diode. The light source driving apparatus of claim 11, wherein the light source power supply further comprises a second diode connected between an input terminal and an output terminal of the switching element. The light source driving apparatus of claim 11, further comprising a resistor connected between an input terminal and a control terminal of the switching element. The light source driving apparatus of claim 11, further comprising a capacitor connected between an output terminal of the switching element and a ground terminal. The display apparatus of claim 5, further comprising a booster configured to boost the first output voltage and the second output voltage to generate a third output voltage and a fourth output voltage. The light source driving unit drives the light source based on any one of the first to fourth output voltages. The method of claim 17, wherein the light source driving unit, A switching mode power supply (SMPS), The boosting unit, An inductor connected between the light source power supply and the switching mode power supply; And And a third diode having an anode connected to the switching mode power supply and the inductor and a cathode connected to the light source. A display module configured to receive light and display an image; And Comprising a light source unit for providing light to the display module including a plurality of light source blocks, and a reference voltage and the light source input voltage to generate a first output voltage close to the light source input voltage or the first output voltage close to the reference voltage And a backlight assembly including a light source power supply unit and a light source driver driving the light source unit based on one of the first output voltage and the second output voltage. The display device of claim 19, wherein the light source unit comprises a plurality of light-emitting diodes (LEDs), and the light source blocks are arranged in one direction.

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